Articles used to absorb waste body fluids such as urine, blood, menses, and the like, are used in large quantities worldwide. These articles are commonly referred to as being “absorbent articles”. Typically, these articles are in the form of diapers, and other like products, such as, feminine hygiene products and incontinence products, which have become increasingly popular as a modern convenience and necessity.
Absorbent articles in the form of diapers generally come in two varieties, namely, reusable cloth diapers and disposable diapers. Modern cloth diapers come with liners, including flushable liners, which hold the waste and permit disposal into a toilet or the like. Disposable diapers greatly increased in popularity following the introduction of superabsorbent polymers (SAP) in diapers in the mid-80s and today, an estimated 90% of U.S. parents use disposable diapers.
A basic disposable diaper includes the following components: (a) an inner layer or top sheet that sits next to the baby's skin and thus, serves as the initial layer that contacts waste fluids; (b) an absorbent core that absorbs and holds the fluids (most absorbent cores are made of fluff made from wood pulp fibers or corn/wheat based materials and include crystals (SAP) that are dispersed throughout the fluff such that the fluff serves to distribute the fluid, while the SAP is intended to absorb the fluid and lock it in the core away from the baby); and (c) a waterproof outer shell or layer (back sheet) that provides a waterproof coating/layer (this layer is most often made of some kind of petroleum-based plastic or plastic-treated material; however, some green diaper companies are using plant-based plastic (aka bioplastic) to provide this layer). The top sheet is most commonly prepared from woven, nonwoven, or porous formed-film polyethylene or polypropylene materials. Back sheet materials typically comprise flexible polyethylene sheets along with the film barrier. The back sheet can be formed as the same material as the top sheet; however, the back sheet includes the film barrier (that acts as a fluid barrier for leak proofing the diaper) on the inner surface of the back sheet. The outer surface of the back sheet comprises the back sheet material (e.g., nonwoven polyethylene) which is soft to the touch and the film barrier is concealed in a traditional diaper construction.
Due to the widespread use of disposable diapers, large quantities of disposable infant diapers are used each year and disposal of these products is a problem. Most of the commercially available disposable diapers consist largely of plastics based on polypropylene and polyethylene which do not break down in the environment, that is they resist biodegradation totally.
In fact, the average disposable diaper can take 500 years to decompose and contains petroleum, plastics, perfumes, wood pulp, and dioxins.
In particular, in many if not most disposable diapers, the liquid permeable surface material and the leak-proof backing material are not biodegradable, although the liquid absorbing material made of fluffed pulp exhibits biodegradability. Consequently, when the diaper is disposed into the ground, the surface material and the backing material remain without being degraded. For the purpose of complete disposal, therefore, it has been necessary to burn the whole diaper or to separate the liquid-permeable surface material and the leak-proof backing material from the top sheet layer for separate disposal.
A further difficulty associated with prior art disposable diapers is that due to the large percentages of toxic chemicals in these products, rashes and skin allergies often arise in the user. Due to the requirements to maximize the absorbency of these products, the quantities of added toxic chemicals have been increased, further compounding the associated problems
Biodegradability and odor is an issue with the nonwovens industry, specifically for diapers, incontinence and feminine hygiene markets. Since the absorbent articles by nature are designed to absorb and contain waste, one of the issues faced with using such products is unpleasant odors emanating from such products after they have become soiled. Odor control in absorbent products has been under investigation for many years. Many body fluids have an unpleasant odor, or develop such odors when in contact with air and/or bacteria for prolonged periods. There is therefore a perceived need to create an improved odor control agent that can be effectively incorporated into an absorbent article.
Other absorbent articles, such as feminine hygiene products and incontinence products, have similar constructions as the disposable diaper described above. There are no products currently on the market that meet the needs of those markets with non-antimicrobial protection.
Even though, a typical disposable diaper, for example, consists of a substantial amount of biodegradable materials, e.g., wood pulp fibers, and the like, there is a need for reducing the amount of non-biodegradable materials in disposable absorbent articles. There is a particular need to replace polyethylene back sheets in absorbent articles with liquid impervious films comprised of biodegradable materials, because the back sheet is typically the largest non-biodegradable component of an absorbent article.
There is further a need to replace odor absorbing materials with those made of natural and/or biodegradable materials.
WO 2016/023016 A1 discloses a disposable diaper that is biobased and/or biodegradable. The diaper is comprised of a biobased and/or biodegradable outer sheet impermeable to aqueous medium, a biobased and/or biodegradable inner sheet permeable to aqueous medium, and absorbent pad made of natural fibers and biobased superabsorbents, and biobased and/or biodegradable side sheets, fastening tabs and elastic waist strip. In particular, the outer sheet, inner sheet, side sheets, fastening tabs and fastening mat are said to be made of a thermoplastic polymer selected from the group consisting of aliphatic polyester, aromatic polyester, cellulosic fiber, nonwoven material and combinations thereof. Superabsorbents can be cellulosic based, starch based or protein based.
Biobased superabsorbent such as the cellulosic based, starch based or protein based absorbents taught in WO 2016/023016 A1 tend to clump and do not hold moisture as well as other materials that are not considered as biobased, but are still biodegradable. Further, an issue with certain thermoplastic polyesters and cellulosic fibers, such as those disclosed in WO 2016/023016 A1, is that they do not degrade in all conditions. Accordingly, use of these materials in a natural fiber containing diaper makes it difficult, if not impossible, for them to pass biodegradability tests such as ASTM Test Method D5511-12, ASTM Test Method 5338.92 or ISO CD Test Method 14855. Applicant is unaware of any diaper products actually able to pass any of ASTM D5511-12, ASTM Test Method 5338.92 or ISO CD Test Method 14855.
What is desired, therefore, are biodegradable absorbent structures that can degrade in conditions in which oxygen is, or is not, present, i.e. both aerobic an anaerobic conditions. What is also desired is a diaper comprised entirely or substantially of biodegradable materials that is compostable and/or will degrade in a landfill. In particular, it is desired to have absorbent articles that are able to pass at least one of ASTM Test Method D5511-12, ASTM Test Method 5338.92 and ISO CD Test Method 14855. It is further desired that a disposable diaper is able to pass at least one of ASTM Test Method D5511-12, ASTM Test Method 5338.92 and ISO CD Test Method 14855. It is further desired that such absorbent articles and diapers contain odor absorbing materials made of natural and/or biodegradable materials. It is also desired that any such diaper have an outer layer that is impermeable to fluids yet has soft hand feel on its outward facing surface.